Background
One third of informal caregivers of people with Alzheimer’s dementia suffer from depression – a percentage greater than the prevalence of depression in the general population or even among caregivers to patients of other psychiatric or physical illnesses [
1,
2]. In addition to the harmful effects for those affected, depression also leads to high direct and indirect costs in Germany every year [
3]. In 2018, depressive episodes were the third most frequently reported cause of absences from work [
4]. Informal caregivers‘depressiveness in particular has been associated with, among other things, higher health care costs [
5], suicidal ideation [
6], more frequent conversion to nursing homes of the person with dementia (PWD) [
7,
8], and more cardiovascular diseases of the informal caregiver [
9].
Seeing as dementia is on the rise both in Germany and worldwide [
10,
11] and most PWD are cared for at home by their relatives rather than moving to a nursing home [
12,
13], there is a pressing need to determine which factors have a central influence on the depressiveness of informal caregivers to be able to derive interventions. Multiple systematic reviews have been written on this topic. Common predictors and correlates of caregiver depression include behavioral and psychological symptoms, female gender of caregivers, being the spouse of the PWD, low social support, competence and coping strategies of the caregiver [
1,
14‐
16]. Other studies have found correlations between depression and dementia severity [
17,
18], lower caregiver education [
19,
20], or ADL dependence [
21]. However, two facts stand out when reviewing previous literature on this topic: for one, most studies feature a cross-sectional design [
14,
15], which makes the direction of causation unclear. And for another, few studies are based on a theoretical framework, seeming to choose their sets of analyzed predictors more due to the convenience of available data from existing studies (for an exception of a study embedded in a theoretical model, see for example Piercy et al. [
19]). That is why the current study aimed to a) employ a longitudinal design in its prediction of change in depressiveness in addition to the cross-sectional view, and b) base the selection of predictors on a theoretical model. The current study refers to data from a dementia register, which collected a wide range of variables over multiple points in time. To select potential influencing factors on the depressiveness of informal caregivers out of this plethora of variables on a theoretical basis, the authors used the stress process model by Pearlin et al. [
22]. This model examines how stress of informal caregivers arises in the care of PWD and considers different groups of predictors, mediators and outcomes (including depression).
The research question addressed here is: What factors influence the change in depressiveness of informal caregivers of a community-dwelling PWD over the course of 1 year?
Results
Sample description
Of the 364 PWD and 339 informal caregivers which participated in BayDem at baseline, 166 dyads met the above criteria as outlined under ‘statistical analysis’. One hundred eigthy-nine informal caregivers provided information on their depressiveness at t0 and t12. Compared to the 141 dyads where informal caregivers had given information on their depressiveness at t0 only, these 189 dyads consisted of significantly younger PWD (F(1, 329) = 6.47, p = .011), with higher levels of cognition (Welch’s F(1, 255.80) = 10.89, p = .001) and less behavioral symptoms (F(1, 318) = 4.26, p = .040), as well as less comorbidities in the informal caregivers (Welch’s F(1, 168.77) = 4.67, p = .032). No difference was observed on the initial level of depressiveness (F(1, 329) = 1.61, p = .205), indicating the missing values to be missing at random. Of the 189 dyads, 23 dyads were excluded because the PWD had an MMSE > 26. In addition, for all subanalyses with care time, 6 dyads were excluded because their sum of ADL, iADL and supervision time per day exceeded 24 h.
Most of the PWD had the diagnosis ‘unspecified dementia’ (F03, 30%), followed by ‘dementia in Alzheimer disease with late onset’ (F00.1, 18%) and ‘dementia in Alzheimer disease, atypical or mixed type’ (F00.2, 11%). For 14% of participants, information about the diagnosis was not yet available at baseline for various reasons. All other diagnosis subcategories had group sizes smaller than 5%.
Tables
2 and
3 show the characteristics of the sample at t0. Two-thirds of the informal caregivers were female, while the proportion of women among the PWD was more balanced at 55%. The informal caregivers were distinctly younger (M = 61.8 years, SD = 12.9) compared to the PWD (M = 78.8 years, SD = 8.8). In about half of the cases (
n = 79), the informal caregivers were the partners of the PWD. In the remaining 86 cases, the majority (
n = 67) were adult (in-law) children. Since few informal caregivers (
n = 19) indicated a different relationship, the variable “relation to the PWD” was dichotomized into partner and non-partner. Partners were significantly older than non-partners (
r = .70,
p < .001) and more often lived in the same household as the PWD (
r = .73,
p < .001). With a mean value of 11.5 (SD = 7.9), the informal caregivers were on average moderately burdened by the caregiving (for norm values see [
30]). Measured by the mean value of 17.9 points for the MMSE (SD = 5.9), the PWD were on average moderately cognitively impaired [
37].
Table 2
Characteristics of PWD and the care situation at baseline and correlations with depressiveness
PWD |
Age c | 166 | 78.8 (8.8) | −.11 (.151) | −.02 (.838) | .10 (.221) |
Female c | 166 | 91 (54.8%) | .07 (.392) | .22 (.004) | .18 (.023) |
Cognition (MMSE) a,c | 147 | 17.9 (5.9) | .07 (.408) | .09 (.309) | .03 (.756) |
∆ Cognition (MMSE) a,b | 118 | −1.9 (5.4) | −.07 (.483) | .18 (.049) | .28 (.002) |
Comorbidities (Charlson Comorbidity Index) a | 148 | 1.9 (2.1) | −.26 (.001) | −.10 (.213) | .15 (.071) |
∆ Comorbidities (Charlson Comorbidity Index) a | 137 | −0.4 (1.7) | .05 (.589) | −.03 (.744) | −.08 (.374) |
Care situation |
Behavioral and psychological symptoms (NPI) a | 161 | 23.4 (20.8) | −.37 (< .001) | −.31 (< .001) | .04 (.610) |
∆ Behavioral and psychological symptoms (NPI) a | 146 | −2.8 (17.9) | .09 (.296) | .10 (.249) | .02 (.793) |
Average care time in hours per day (RUD) |
Help with ADL a | 152 | 1.1 (1.6) | −.14 (.102) | −.10 (.233) | .03 (.775) |
∆ Help with ADL a | 138 | 0.1 (1.3) | .01 (.893) | −.10 (.221) | −.13 (.128) |
Help with iADL a | 152 | 2.1 (2.1) | −.08 (.330) | −.08 (.361) | −.00 (.966) |
∆ Help with iADL a | 136 | 0.0 (2.0) | −.01 (.907) | −.04 (.666) | −.03 (.703) |
Supervision a,c | 149 | 3.3 (5.0) | −.29 (.001) | −.34 (< .001) | −.09 (.285) |
∆ Supervision a,b | 134 | 0.5 (4.1) | .11 (.190) | −.08 (.382) | −.20 (.024) |
Table 3
Characteristics of informal caregivers at baseline and correlations with depressiveness
Informal caregivers |
Age a,b,c | 165 | 61.8 (12.9) | .08 (.331) | −.10 (.201) | −.19 (.017) |
Female a c | 165 | 118 (71.5%) | −.20 (.010) | −.23 (.004) | −.05 (.567) |
Relation to PWD (partner) a,b | 165 | | .05 (.513) | −.14 (.067) | −.21 (.007) |
Child, relative, other | | 86 (52.1%) | | | |
Partner | | 79 (47.9%) | | | |
Same household as PWD | 165 | 105 (63.6%) | −.03 (.747) | .16 (.042) | −.15 (.058) |
Highest school degree a | 164 | | .05 (.554) | .16 (.037) | .13 (.098) |
No school degree | | 1 (0.6%) | | | |
Volksschule (primary school) | | 34 (20.7%) | | | |
Hauptschule (secondary school) | | 48 (29.3%) | | | |
Mittlere Reife (secondary school certificate) | | 48 (29.3%) | | | |
Fachhochschulreife (advanced technical college certificate) | | 11 (6.7%) | | | |
Abitur (high school certificate) | | 22 (13.4%) | | | |
Place of residence (rural) | 166 | | −.21 (.008) | −.15 (.050) | .04 (.595) |
Urban | | 112 (67.5%) | | | |
Rural | | 54 (32.5%) | | | |
Social inclusion (LSNS) a | 118 | 30.5 (9.9) | .22 (.017) | .29 (.001) | .09 (.316) |
∆ Social inclusion (LSNS) a | 114 | −0.6 (8.3) | −.03 (.782) | .03 (.731) | .06 (.532) |
Care contribution (RUD) a | 138 | 4.3 (1.11) | −.29 (.001) | −.19 (.024) | .06 (.486) |
∆ Care contribution (RUD) a | 121 | 0.2 (1.0) | .00 (.996) | .03 (.768) | .04 (.688) |
Caregiver burden (BSFC-s) | 162 | 11.5 (7.9) | −.57 (< .001) | −.46 (< .001) | .07 (.388) |
Comorbidities (Charlson Comorbidity Index) | 124 | 0.6 (1.0) | −.10 (.274) | −.12 (.203) | −.03 (.774) |
Depressiveness (WHO-5) c | 166 | 51.2 (23.6) | . | .55 (< .001) | −.41 (< .001) |
Compared to a German norm sample [
39] of similar age (M
WHO-5 = 66.8, SD
WHO-5 = 20.5), the informal caregivers of the present sample (M
WHO-5 = 51.2, SD
WHO-5 = 23.6) were above average depressed. This difference is statistically significant, t(165) = − 8.49,
p < .001. In relation to the cut-off of 50, 46% of the informal caregivers fall into the range where depression is likely (see Table
4). The arithmetic mean of the depressiveness score according to WHO-5 barely varies in the sample within 12 months (M
t12 = 50.9; SD
t12 = 25.6). However, 18% change from the likely depressed group to the unlikely depressed group and 13% vice versa. The change scores of depressiveness from t0 to t12 show a wide range (from − 68 to + 64, SD = 23.4) with approximately normal distribution. Thus, even though the mean of depressiveness at t0 lies close to the cutoff, it seems unlikely that group changes were merely caused by minor fluctuations of the score.
Table 4
Means of informal caregiver depressiveness and dichotome groups according to cut-off ≤50
N | 166 | 166 |
| M | SD | M | SD |
Depressiveness (WHO-5) | 51.2 | 23.6 | 50.9 | 25.6 |
| n | % | n | % |
likely depressed | 77 | 46.4% | 70 | 42.2% |
change from t0 |
stayed likely depressed | | | 48 | 28.9% |
turned likely depressed | | | 22 | 13.3% |
stayed unlikely depressed | | | 67 | 40.4% |
turned unlikely depressed | | | 29 | 17.5% |
At baseline, the depressiveness of informal caregivers was significantly higher when the PWD had more comorbidities and more psychological and behavioral symptoms, and also when the informal caregiver spent more time supervising the PWD, was female, resided in a rural area, had low social inclusion, high personal contribution to care, and high caregiver burden (see Tables
2 and
3). An increase in the depressiveness of informal caregivers over 12 months had a significant bivariate association with the gender of PWD (more common in caregivers of male PWD), their declining cognition, an increase in supervision time, higher age of informal caregivers at baseline, being the partner of the PWD, and low baseline depressiveness (Tables
2 and
3).
Multivariate factors influencing the change in depressiveness
In Tables
2 and
3, those variables that were considered for the regression model due to Pearlin’s stress process model are marked with an
a. Of these, the variables that correlated significantly with the change in depressiveness scores are marked with a
b. These variables were included in the regression model as potential predictors, and additionally, in the case of the change variables, the initial value of the respective variable for adjustment as well as gender and age of PWD and informal caregivers as basic demographic control variables and baseline depressiveness for adjustment. These variables added due to methodological considerations are marked with a
c. The variable “relation to the PWD” was excluded due to multicollinearity (VIF = 7.79). As mentioned above, older informal caregivers were significantly more often the partner of the PWD.
Due to listwise exclusion of cases, the regression featured a final sample size of 98. As Table
5 shows, the multiple regression model used to predict the change in depressiveness over 1 year was significant, F (8, 89) = 4.20,
p = < .001,
R2 = 0.23. In addition to low baseline depressiveness, an increase in supervision time proved to be a significant predictor of worsening depressiveness. High supervision time at t0 lay at the threshold of significance with
p = .058.
Table 5
Predictors of the change in informal caregiver depressiveness from t0 to t12
Variable | b | SE | Β | p | VIF |
Constant | 2.62 | 27.70 | | .925 | |
Depressiveness t0 (WHO-5) | − 0.35 | 0.09 | −.35 | < .001 | 1.11 |
Age PWD | −0.01 | 0.28 | −.00 | .974 | 1.21 |
Gender PWD (female) | 9.60 | 5.82 | .21 | .103 | 2.13 |
Age informal caregiver | 0.09 | 0.19 | .05 | .619 | 1.49 |
Gender informal caregiver (female) | −2.06 | 5.96 | −.04 | .730 | 1.56 |
Cognition t0 (MMSE) | 0.16 | 0.38 | .04 | .682 | 1.33 |
∆ Cognition (MMSE) | 0.48 | 0.42 | .12 | .256 | 1.42 |
Supervision t0 (RUD) | −1.12 | 0.58 | −.25 | .058 | 2.12 |
∆ Supervision (RUD) | −1.46 | 0.56 | −.29 | .010 | 1.55 |
Discussion
The present study is a multicenter investigation in three regions in the Free State of Bavaria. The large number of variables included as well as the longitudinal design allowed for the investigation of influencing factors of the change in depressiveness of informal caregivers of PWD. The data of 166 informal caregivers and their PWD were analysed, showing higher depressiveness than in a German norm sample of similar age, with 46% screening as depressed. Interestingly, an increase in supervision time over 1 year significantly predicted an increase in depressiveness over the same timespan, even when controlling for age, gender, baseline depressiveness and cognition.
As has been shown in other studies [
1,
2], informal caregivers of PWD represent a risk group for depression. Almost half the group of participating informal caregivers in this study seemed likely to have developed clinically relevant symptoms of depression and should be advised to seek further diagnosis. What is it that puts informal caregivers of PWD more at risk of negative mental outcomes than the general population or even caregivers of other illnesses? The fact that caregiving overall negatively affects psychological health is a widely-known phenomenon and attributed in part to the fact that caregiving “often restricts the personal life, social life, and employment of the caregiver” ([
40], p.250) and produces uncertainty due to the unforeseeable evolvement of the care receiver’s symptoms. Now, with dementia in particular, that strain is heightened further due to the presence of behavioral and psychological symptoms of the PWD, such as aggression, paranoia, or sleep disturbances. Behavioral and psychological symptoms in dementia have been linked to poor mental health of informal caregivers of PWD [
14,
41].
The high prevalence of depressive symptoms in informal caregivers of PWD highlights the importance to act and find modifiable factors to reduce mental distress, especially in light of the high resulting cost for society as a whole (e.g. higher health care cost [
5]) and the affected people themselves (e.g. higher suicidal ideation [
6]). Cross-sectional connections to depressiveness in this study are similar to those found in previous research (e.g. behavioral and psychological symptoms [
14], social support [
17,
42], or female gender of PWD [
1]). This holds particularly true for the close connection between depressiveness and caregiver burden. In their meta-analysis of 2019, Del-Pino-Casado et al. found correlations of around
r = .5 between depression and subjective caregiver burden among caregivers in general, with even higher values among caregivers of PWD [
43]. These findings are very similar to the correlation coefficient of
r = .57 observed in this study.
However, a look at the longitudinal data seems interesting. If one controls for age and gender of PWD and informal caregivers as well as the baseline score of depressiveness, cognition or its decrease no longer show a significant association with the change in depressiveness, but supervision time (marginal) as well as its increase do. This might indicate that it is not the disease symptoms per se that are responsible for the poor mental health of informal caregivers, but rather the resulting need for supervision of the PWD. Also, caregivers higher in age were usually the partner of the PWD and more often lived in the same household. Yet similar to cognition, age of the caregiver lost its significant association with change in depressiveness when in a model with supervision time. In that vein, it might not be the high age of the caregiver or their subsequent state as a partner to the PWD living in the same household which might increase mental distress by having to provide a deeper level of caregiving [
1,
41] or due to the difficult adjustment to a changed relationship [
44], as previous studies have suggested, but rather the strain of constant vigilance emerging from rising supervision time. This might also be one of the reasons why informal caregivers of PWD are more depressed than caregivers of other groups, as supervision time is higher in the care of PWD than of people without dementia and has been shown to rise with increasing dementia severity [
45‐
48].
Even though with an R
2 of 0.23, 77% of the variance in change in depressiveness is still left unaccounted for in the regression model, the coefficient of determination can be interpreted as almost reaching a large effect (
R2 = 0.26) according to Cohen [
49]. Change in supervision time was one of only two predictors to reach significance in this model. But why might supervision of the PWD be so burdensome to the caregiver? Supervision is by far the most time-consuming part of informal care when compared to helping with ADL and iADL [
47,
48,
50]. Informal caregivers have to prevent dangerous events, like falls or accidents with fire, manage behavioral symptoms, such as wandering or aggression, and even deal with potentially embarrassing behaviors, such as urinating on the floor [
51]. Studies show that the informal caregivers often feel the need to constantly supervise, just in case something happens [
51,
52], and it might be that strain of constantly fearing for something dangerous or embarrassing to happen to their care receiver which causes stress to the informal caregiver. Stress is the basis of Pearlin’s stress process model, leading eventually to such negative outcomes as depression [
22]. Perhaps an important mediating factor here might be anxiety of the informal caregiver, which has been linked to behavioral disturbance in dementia [
15,
53], which in turn correlates with supervision time [
51]. Anxiety has been shown to often occur alongside depression [
54,
55]. Anxiety was unfortunately not a part of this data set and is rarely the focus of research concerning informal caregivers [
15], but could help illuminate the relationship between supervision time and depression. Further research is needed to examine whether behavioral and psychological symptoms in dementia and the consequent anxiety over the PWD entering dangerous or embarrassing situations perhaps increase both supervision time and caregiver depressiveness.
Furthermore, the current study used Pearlin’s stress process model [
22] as theoretical framework for the selection of variables. Unfortunately though, two categories of predictors – secondary role strains and secondary intrapsychic strains – could not be fitted to variables assessed within the BayDem data set. Future research might benefit from investigating the impact on caregiver depression under account of
all categories of Pearlin’s model in a longitudinal study design.
Strengths and limitations
As there is no population register for informal caregivers of PWD that could be used for recruitment, the study population is not representative for all informal caregivers in Bavaria. However, recruitment of participants took place through a variety of institutions, such as counseling centers, registered doctors and therapists, medical care centers, memory clinics, nursing services, volunteer services and hospitals, with the aim of obtaining data that is as valid as possible. A special feature of the study is also that the three study regions have different geographical, demographic and socio-economic profiles and different population trends. While the rate of refusal for study participation could not be assessed due to time constraints in the recruiting institutions, there is little evidence towards a selection bias, as age (M = 61.8 years) and gender (72% women) of the final sample of informal caregivers in this study are quite similar to that of study samples in other studies on Bavarian informal caregivers (e.g. M
age = 61.3 years, 76% women [
30]).
There are missing data in the follow-up. Of the 339 participating informal caregivers, 56% completed follow-up after a year. However, this is average for European studies involving informal caregivers [
56]. Those dyads which dropped out of the study featured higher age, lower cognitive function, and more behavioral symptoms in the PWD as well as more comorbidities in the informal caregivers than non-dropouts. This is to be expected, as both severity of dementia and physical impairment of the caregiver may lead to study dropout due to institutionalization of the PWD, death of the participants, or the informal caregivers no longer feeling able to continue study participation. No effect could be observed of the dropped-out informal caregivers being more depressed at baseline than the non-dropouts. In addition, the interviews were conducted in the home environment of the PWD, which allowed a realistic picture of the living situation of the PWD to be obtained.
It was found that change in supervision time, a modifiable variable, predicted change in depressiveness. Due to the lack of experimental design however, a causal conclusion cannot be drawn without doubt regarding the relationship between these two variables. An interventional study aiming to impact the time spent on supervision would be required to do so. Nevertheless, longitudinal register research is still preferable over cross-sectional observation, and many different variables were able to be included in the analysis.
As suggested in the systematic review by Topp and colleagues [
36], the depressiveness scores were multiplied by 4 in order to achieve a range of scores from 0 to 100 and to be better comparable with other studies using the WHO-5. However, it must be considered that this artificial transformation of the values feigns a higher accuracy than is actually present.
Finally, even though several studies found adequate sensitivity and specificity for the WHO-5 as a screening tool for depression [
36], it should be stressed that a score below 50 does not prove the presence of clinical depression but should rather encourage to conduct further diagnostics. Thus, it cannot be said that 46% of the study population were clinically depressed but rather that clinical depression is likely in this group. However, the aim of the study was not to diagnose informal caregivers with depression but rather to find predictors of the change of depressive symptoms over time, which the study was able to achieve, as the WHO-5 is a valid instrument for screening for depression [
36] and yields similar results as other depression scales [
57‐
59].
Practical implications
Following the results of this study, practical implications can be drawn in regard to both direct and indirect relief of informal caregivers of PWD. In order to possibly lower depressiveness of informal caregivers, supervision time of the PWD should be reduced. This can be done by promoting support services for informal caregivers so that they can take time for themselves to recuperate. Examples of such services might be day care centers, care services, organized neighborhood assistance as well as short-term or respite care. Support services are currently still used to a small extent [
60‐
62]. The successor study to BayDem, digiDEM Bayern, plans to assess use of and need for support services in Bavaria as well as reasons why support services might not be used by caregivers and their PWD [
63]. This way, potential barriers to service use might be found and actions for their removal might be recommended to major decision makers.
Indirect relief for the caregivers on the other hand can be achieved by trying to delay the course of the disease as much as possible to keep the necessary supervision time low. Some psychosocial interventions have proven successful in this aspect. One of them is the evidence-based, multi-component MAKS therapy, which includes exercises for social activation, sensorimotor activation, cognitive activation and activation of ADL. A randomized controlled study was able to show MAKS therapy’s effectiveness in stabilizing the outcomes “cognitive abilities”, “ADL abilities” and “neuropsychiatric symptoms” over 6 months as compared to usual care [
64]. Thus, effective psychosocial interventions might be able to reduce the need for care by family caregivers by keeping practical everyday skills longer.
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